I like Fran's idea to just use the other side if you can get it out. The oil sender doesn't care what side it's on. Welding a nut (or bolt) on sound like a fantastic idea. Heat won't hurt a thing if you've got a torch. All those ideas will work.
As far as the "T" you might see in some pictures (and related stuff). "Sometimes" there's a clearance issue between the sending unit and the block (?) or something, especially with an aftermarket sending unit, and you have to space the sending unit up & out of the way with an "oil sending unit extension tube". Also, if you want to keep your factory gauge AND run a mechanical gauge too, you need to put a "T" in there so you can run both gauges.....or tap the mechanical gauge into that other plug Fran suggested you use. It is as simple as it looks.